Drill lubricant



' Patented Oct. 1, 1946 DRILL LUBRICANT Edmund L. Flood, San Diego, Calif., 'assignor to Consolidated Vultee Aircraft Corporation, San Diego, Calif., a corporation of Delaware No Drawing. Application April 16,1945, Serial No. 588,733

9, Claims. (01. 25%-41) This invention relates, to lubricants for drills of the portable and stationary types which are used, to drill holes, through metal. and more particularly to. asodium base grease lubricant composition: which is especially adapted for use in .high. speed hand drilling operations in the manufacture of aircraft.

V In the high speed hand drilling of metals in the aircraft industry,: particularly aluminum alloys such as duralunnn there has been up to the present time a pressin need for a lubricant which'will stay cnthe drill during rotation thereof and remain stable during the Vigorous mechanical agitation and high temperature conditions to which such lubricants are subjected during drilling operations. The lubricants heretofore used in these operations are objectionable because they either fly off the revolving drill,

leaving insuflicient lubricant on the drill and soil-' ing everything on which the flying lubricant settles, or are unable properly to lubricate the drill during operation because they disintegrate under the high temperature conditions generated by the drilling operation. Not infrequently, with such prior art lubricants, it was found that the duralumin welded to the revolving drill point, resulting in imperfect drillingsand in the need to discard costly drills long before the useful life thereof had been fully utilized.

The lubricant composition of the present invention overcomes the foregoing defects inherent in the prior art lubricants used in high speed drilling operations and, additionally, makes possible the drilling of perfect holes through superimposed sheets of duralumin and other metals without elongation of the hole in the outer sheet.

Also, it maintains the temperature generated.

during drilling lower than heretofore, by as much as 25% and even more, thereby prolonging the life and productivity of the drill. The lubricant composition of my invention has other advantages which will be made apparent in the following description of the composition.

The drill lubricant composition of my invention comprises a soda base grease, turpentine; a relatively highmelting point wax, preferably a petroleum wax, and aluminum stearate. The proportions of the constituents of my composition are critical in that any substantial variation from the proportions set forth in the preferred illustrative embodiment set forth below will impair the effectiveness of the composition as a drill lubricant. In general, on a weight basis, the soda base grease may vary from about 45 to 52% of the composition; the turpentine from 8 to 12%,

' 2 the wax f:om 38 to 43%, and the aluminum stearate from 0.25 to 0.5%.

The soda base grease may be produced by suspending or dissolving sodium soap produced from 5 vegetable or animal oils or fats or fatty acids in a mineral oil. Thus, this grease may be formed by incorporating into a suitable mineral oil, prefer- .ably one having high dash and fire points, a desired percentage, say about 15 to 50%, of the sodium soap of tallow, stearic acid, hydrogenated fatty acids or the. like or the sodium soap of any mixture of soap forming stocks. The most effective soda base grease is. one: produced by incorporating from about to 23% of a sodium 15 base soap, based on the weight of the grease, in a high viscosity lubricating oil or a mixtur of such oils which contain dissolved or suspended therein a small amount, say 1 to 1.4%, of petrolatum. The preferred lubricating oil is petroleum Bright Stock alone or in combination with a mineral lubricating oil having a viscosity of 550 seconds, Saybolt, at 100 F.

The relatively high melting point wax of the composition of my invention is paraffin wax hav- 25 mg a melting point higher than the melting melting points above about 143 F. such as I points of the typical varieties of paraffin wax commercially available. Thus, the paraffin Wax may have a melting point of about 143 to 170 F., preferably 160t0 165 F. Other waxes having carnauba Wax, ceresin wax, candelilla wax and the like may be used, but better results ar obtained with paraflin wax.

The following is an example of a preferred drill lubricant in accordance with my invention and of the method of making it. In the example, the term parts indicates parts by weight.

The soda base grease, turpentine and alumi- 5 num stearate are mixed at room temperature,

then heated to about 165 Rand then thoroughly mixed with'the parafiin wax while the latter is in the melted state. The mixture, while still hot, is poured into a container and permitted to cool and solidify.

The grease of my composition serves as a vehicle for the turpentine, the cutting oil, and acts to give a smooth finish to the Walls of the hole being drilled. The relatively high'percentage of mineral oil in the soda base grease serves as an 3 excellent heat conductor and makes possible the drilling through metal at temperatures lower than heretofore. The relatively large amount of relatively high melting point wax of my composition serves to maintain the drill lubricant in a solidified state and prevents the oil and turpentine from draining therefrom. The aluminum stearate aids in making the composition uniform and stable and imparts film strength to the mineral oil, thereby augmenting the anti-Welding properties of the lubricant composition and making possible the drilling through metal of sharp, clean holes without Welding of chips or turnings to the drill point.

The herein described lubricant eifectively and efficiently fulfills its intended purpose and may be applied to a drill in any suitable manner such as,

for example, by inserting the drill into a closed cardboard container filled with the lubricant.

I claim:

1. A drill lubricant composition comprising, on a weight basis, from 45 to 52% of a soda base grease, 38 to 43% of parafiin wax having a melting point of at least about 143 F., 8 to 12% of turpentine and 0.25 to 0.5% of aluminum stearate.

2. The drill lubricant of claim 1 wherein the soda base grease comprises, on a weight basis, from 15 to 23% of a sodium base soap,

3. The drill lubricant of claim 1 wherein the soda base grease comprises, on a weight basis, from 15 to 23% of a sodium base soap and from 1 to 1.4% of petrolatum.

4. The drill lubricant of claim 1 wherein the soda base grease comprises, on a weight basis, from 15 to 23% of a sodium base soap, the balance being petroleum Bright Stock and 550 viscosity lubricating oil, together with about 1 to 1.4% of petrolatum.

5. A drill lubricant composition consisting of, on an approximate weight basis, parts of soda base grease, 43 parts of parafiin wax having a melting point of about 165 F., 10.4 parts of turpentine and 0.42 part of aluminum stearate.

6. The drill lubricant of claim 5 wherein the soda base grease comprises, on an approximate weight basis, 17% of soda base soap and in excess of of a high-viscosity lubricating oil.

'7. The drill lubricant of claim 5 wherein the soda base grease comprises, on an approximate Weight basis, 17% of soda base soap and in excess of 80% of a high-Viscosity lubricating oil consisting of petroleum Bright Stock and 550 viscosity lubricating oil. 7

8. The drill lubricant of claim 1 wherein the soda base grease comprises, on a weight basis, from 15 to 23% of a sodium base soap suspended in a vehicle consisting essentially of petroleum Bright Stock and 550 viscosity lubricating oil.

9. The drill lubricant of claim 1 wherein the soda base grease comprises, on a weight basis, from 15 to 23% of a sodium base soap suspended in a vehicle consisting essentially of a high-viscosity lubricating oil.

EDMUND L. FLOOD. 

